Stylesheet problem with 9.0.2 upgrade

I upgraded from 8.3 to 9.0.2. The main forum pages are fine but I have style sheet problems when I go to a topic. My style sheet is three columns. In IE6, in a post, the main column is wrapping onto my left column, and obliterating most of my right column. I never had this problem with 8.3.

Firefox2 is readable. But there is a blank box with an “Add” button that is creating width problems. Otherwise the columns are sizing correctly.

The solution revolves around IE6 ignoring new classes and ids implemented in the updated software version. Once I figured out what classes or ids were missing and acknowledged them in my stylesheet, then everything fell back into place.